U.S. patent application number 10/583299 was filed with the patent office on 2007-07-26 for free-radical-initiated crosslinking of polymers.
This patent application is currently assigned to Dow Global Technologied Inc.. Invention is credited to Bharat I. Chaudhary, Yunwa W. Cheung, Randall M. Cuntala, Mohamed Esseghir, John Klier.
Application Number | 20070173613 10/583299 |
Document ID | / |
Family ID | 34738802 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070173613 |
Kind Code |
A1 |
Chaudhary; Bharat I. ; et
al. |
July 26, 2007 |
Free-radical-initiated crosslinking of polymers
Abstract
The present invention is a free-radical carbon-FRTS-carbon
crosslinkable polymeric composition. The resulting
carbon-FRTS-carbon crosslinked polymer is prepared from at least
one polymer which upon forming free radicals preferentially
degrades or carbon-carbon crosslinks. The present invention permits
suppression of the preferential reaction while permitting the
polymer to be carbon-FRTS-carbon crosslinked through a free-radical
trapping species. Suppressing the undesirable degradation or
carbon-carbon crosslinking reaction and permitting the desirable
carbon-FRTS-carbon crosslinking reaction yield a uniquely
crosslinked polymer.
Inventors: |
Chaudhary; Bharat I.;
(Princeton, NJ) ; Cheung; Yunwa W.; (Lake Jackson,
TX) ; Cuntala; Randall M.; (Columbia, NJ) ;
Esseghir; Mohamed; (Monroe Township, NJ) ; Klier;
John; (Midland, MI) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION,
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Assignee: |
Dow Global Technologied
Inc.
Washington Street, 1790 Building
Midland
MI
48674
|
Family ID: |
34738802 |
Appl. No.: |
10/583299 |
Filed: |
December 24, 2004 |
PCT Filed: |
December 24, 2004 |
PCT NO: |
PCT/US04/43346 |
371 Date: |
June 16, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60532491 |
Dec 24, 2003 |
|
|
|
Current U.S.
Class: |
525/374 ;
525/326.2; 525/329.1; 525/331.9; 525/333.7 |
Current CPC
Class: |
C08F 8/30 20130101; C08K
5/3435 20130101; C08K 5/14 20130101; C08L 101/00 20130101; C08K
5/3435 20130101; C08L 23/10 20130101; C08L 101/00 20130101; C08L
2666/04 20130101; C08L 23/10 20130101; C08L 23/22 20130101 |
Class at
Publication: |
525/374 ;
525/326.2; 525/329.1; 525/331.9; 525/333.7 |
International
Class: |
C08F 8/30 20060101
C08F008/30 |
Claims
1. A free-radical carbon-FRTS-carbon crosslinkable polymeric
composition comprising: (a) a free-radical degradable polymer, (b)
a free-radical inducing species, and (c) a free radical trapping
species having at least two trapping sites, wherein (A1) the free
radical trapping species (i) substantially suppresses degradation
of the polymer in the presence of the free-radical inducing species
and (ii) at a trapping site, being graftable onto the polymer after
the polymer forms a free radical, and (A2) the free-radical
carbon-FRTS-carbon crosslinkable composition yields a free-radical
carbon-FRTS-carbon crosslinked polymer.
2. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the degradation occurs by chain
scission.
3. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the polymer being halogenated and
the degradation occurs by dehydrohalogenation.
4. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the resulting free-radical
carbon-FRTS-carbon crosslinked polymer having a gel content as
measured by xylene extraction (ASTM 2765) of greater than about 10
weight percent.
5. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the resulting carbon-FRTS-carbon
polymer having a gel content as measured by xylene extraction (ASTM
2765) of at least about an absolute 10 weight percent greater than
the gel content of the base polymer.
6. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the polymer is selected from the
group consisting of butyl rubber, polyacrylate rubber,
polyisobutene, propylene homopolymers, propylene copolymers,
styrene/butadiene/styrene block copolymers,
styrene/ethylene/butadiene/styrene copolymers, polymers of vinyl
aromatic monomers, vinyl chloride polymers, and blends thereof.
7. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the free-radical inducing species
being an organic peroxide, Azo free radical initiator, bicumene,
oxygen, and air.
8. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 1 wherein the free radical trapping species
being a hindered amine-derived free radical trapping species.
9. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 8 wherein the hindered amine-derived free
radical trapping species being selected from the group consisting
of multi-functional molecules having at least two functional groups
of 2,2,6,6,-tetramethyl piperidinyl oxy and derivatives
thereof.
10. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 9 wherein the hindered amine-derived free
radical trapping species having at least two nitroxyl groups
derived from oxo-TEMPO, hydroxy-TEMPO, esters of hydroxy-TEMPO,
polymer-bound TEMPO, PROXYL, DOXYL, di-tertiary butyl N oxyl,
dimethyl diphenylpyrrolidine-1-oxyl, 4 phosphonoxy TEMPO, or metal
complexes with TEMPO.
11. (canceled)
12. A free-radical carbon-FRTS-carbon crosslinkable polymeric
composition comprising: (a) a free-radical degradable polymer and
(b) a free-radical inducing species, and (c) a free radical
trapping species graftable via a free-radical-initiated
carbon-FRTS-carbon coupling bond to the polymer, wherein the
resulting rheology-modified polymer having a Maximum Torque>1.30
* Minimum Torque measured by a moving die rheometer at the
polymer's crosslinking temperature, a frequency of 100 cycles per
minute, and an arc of 0.5 degrees.
13. A free-radical carbon-FRTS-carbon crosslinkable polymeric
composition comprising: (a) a free-radical carbon-carbon
crosslinkable polymer, (b) a free-radical inducing species, and (c)
a free radical trapping species having at least two trapping sites,
wherein (A1) the free radical trapping species (i) substantially
suppresses carbon-carbon crosslinking of the polymer in the
presence of the free-radical inducing species and (ii) at a
trapping site, being graftable onto the first polymer after the
first polymer forms a free radical, and (A2) the free-radical
carbon-FRTS-carbon crosslinkable polymeric composition yields a
free-radical carbon-FRTS-carbon crosslinked polymer.
14. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 13 wherein the resulting carbon-FRTS-carbon
crosslinked polymer having a gel content as measured by xylene
extraction (ASTM 2765) of greater than about 10 weight percent.
15. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 13 wherein the resulting carbon-FRTS-carbon
crosslinked polymer having a gel content as measured by xylene
extraction (ASTM 2765) of at least about an absolute 10 weight
percent greater than the gel content of the base polymer.
16. The free-radical carbon-FRTS-carbon crosslinkable polymeric
composition of claim 13 wherein the carbon-carbon crosslinkable
polymer is selected from the group consisting of acrylonitrile
butadiene styrene rubber, chloroprene rubber, chlorosulfonated
polyethylene rubber, ethylene/alpha-olefin copolymers,
ethylene/diene copolymer, ethylene homopolymers,
ethylene/propylene/diene monomers, ethylene/propylene rubbers,
ethylene/styrene interpolymers, ethylene/unsaturated ester
copolymers, fluoropolymers, halogenated polyethylenes, hydrogenated
nitrile butadiene rubber, natural rubber, nitrile rubber,
polybutadiene rubber, silicone rubber, styrene/butadiene rubber,
styrene/butadiene/styrene block copolymers,
styrene/ethylene/butadiene/styrene copolymers, and blends
thereof.
17. (canceled)
18. A free-radical carbon-FRTS-carbon crosslinkable polymeric
composition comprising: (a) a free-radical carbon-carbon
crosslinkable polymer and (b) a free-radical inducing species, and
(c) a free radical trapping species graftable via a
free-radical-initiated carbon-FRTS-carbon coupling bond to the
polymer, wherein the resulting rheology-modified polymer having a
Maximum Torque>1.30 * Minimum Torque measured by a moving die
rheometer at the polymer's crosslinking temperature, a frequency of
100 cycles per minute, and an arc of 0.5 degrees.
19-29. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention relates to polymer systems that undergo free
radical reactions, wherein introducing a unique
free-radical-initiated crosslink is desirable.
DESCRIPTION OF THE PRIOR ART
[0002] A number of polymers can undergo free radical reactions.
Some of those reactions are detrimental such as degrading or
carbon-carbon crosslinking. There is a need to promote a beneficial
free-radical-initiated crosslinking reaction while minimizing the
impact of the detrimental reactions.
[0003] Polyolefins are frequently subjected to nonselective
free-radical chemistries. For example, free-radical chemistries at
elevated temperatures can degrade the molecular weight, especially
in polymers containing tertiary hydrogen such as polypropylene and
polystyrene. Additionally, free-radical chemistries can promote
carbon-carbon crosslinking, resulting in crosslinked polymers with
limited physical properties.
[0004] With regard to polypropylene, the free-radical degradation
of the polymer may be described as chain scission, lowers the
polymer's molecular weight, and increases its melt flow rate.
Because scission is not uniform, molecular weight distribution
increases as lower molecular weight polymer chains referred to in
the art as "tails" are formed.
[0005] With regard to polyethylene, the free-radical carbon-carbon
crosslinking yield a crosslinked polymer with limited physical
properties. It is desirable to introduce a unique crosslink and
provide a crosslinked polymer with unique physical properties.
[0006] It is desirable to prepare a free-radical crosslinked
polymer, without chain scission or carbon-carbon crosslinking the
polymer. If the polymer is halogenated, it is also desirable that
the polymer not undergo dehydrohalogenation.
[0007] It is also desirable to control the molecular architecture
of the polymer as it undergoes the crosslinking reaction.
SUMMARY OF THE INVENTION
[0008] The present invention is a free-radical carbon-FRTS-carbon
crosslinkable polymeric composition. The resulting
carbon-FRTS-carbon crosslinked polymer is prepared from at least
one polymer which upon forming free radicals preferentially
degrades or carbon-carbon crosslinks. The present invention permits
suppression of the preferential reaction while permitting the
polymer to be carbon-FRTS-carbon crosslinked through a free-radical
trapping species. Suppressing the undesirable degradation or
carbon-carbon crosslinking reaction and permitting the desirable
carbon-FRTS-carbon crosslinking reaction yield a uniquely
crosslinked polymer.
[0009] The present invention is useful in wire-and-cable, footwear,
film (e.g. greenhouse, shrink, and elastic), engineering
thermoplastic, highly-filled, flame retardant, reactive
compounding, thermoplastic elastomer, thermoplastic vulcanizate,
automotive, vulcanized rubber replacement, construction,
automotive, furniture, foam, wetting, adhesive, paintable
substrate, dyeable polyolefin, moisture-cure, nanocomposite,
compatibilizing, wax, calendared sheet, medical, dispersion,
coextrusion, cement/plastic reinforcement, food packaging,
non-woven, paper-modification, multilayer container, sporting good,
oriented structure, and surface treatment applications.
BRIEF DESCRIPTION OF DRAWING
[0010] FIG. 1 shows torque-time curves at 182 degrees Celsius for
free-radical-initiated crosslinkable polymeric compositions with
and without a multifunctional free-radical trapping species.
[0011] FIG. 2 shows torque-time curves at 182 degrees Celsius for
free-radical-initiated crosslinkable polymeric compositions with a
multifunctional free-radical trapping species.
[0012] FIG. 3 shows torque-time curves at 182 degrees Celsius for
free-radical-initiated crosslinkable polymeric compositions with
and without a multiflnctional free-radical trapping species.
DESCRIPTION OF THE INVENTION
[0013] "Carbon-FRTS-Carbon Coupling Bond," as used herein, means
covalent bonds formed between a carbon of a polymer molecule, a
free-radical trapping species, and a carbon of another polymer
molecule. Prior to formation of the carbon-FRTS-carbon coupling
bond (crosslink), the free-radical trapping species has at least
two trapping sites. At two of the trapping sites, the free-radical
trapping species is grafted to the polymer molecules.
[0014] Preferably, the resulting carbon-FRTS-carbon crosslinked
polymer will have a gel content as measured by xylene extraction
(ASTM 2765) of greater than about 10 weight percent, more
preferably, greater than about 30 weight percent, even more
preferably, greater than about 50 weight percent, and most
preferably, greater than about 70 weight percent. The gel content
of the carbon-FRTS-carbon crosslinked polymer will be at least an
absolute 10 weight percent greater than the gel content of the base
polymer (the uncrosslinked polymer).
[0015] Alternatively, the crosslinking density of the
carbon-FRTS-carbon crosslinked polymer will be determined based of
the polymer's modulus. A carbon-FRTS-carbon crosslinked polymer
will preferably have a Maximum Torque of at least about 1.30 times
its Minimum Torque, both measured by a moving die rheometer at the
crosslinking temperature of the polymer, a frequency of 100 cycles
per minutes, and an arc of 0.5 degrees.
MH.sub.H.gtoreq.1.30.times.M.sub.L More preferably, the ultimate
crosslinking density is achieved when the polymer's Maximum Torque
is also about the same as its Final Torque at the crosslinking
temperature.
[0016] "Constrained geometry catalyst catalyzed polymer",
"CGC-catalyzed polymer" or similar term, as used herein, means any
polymer that is made in the presence of a constrained geometry
catalyst. "Constrained geometry catalyst" or "CGC," as used herein,
has the same meaning as this term is defined and described in U.S.
Pat. Nos. 5,272,236 and 5,278,272.
[0017] "Metallocene," as used herein, means a metal-containing
compound having at least one substituted or unsubstituted
cyclopentadienyl group bound to the metal. "Metallocene-catalyzed
polymer" or similar term means any polymer that is made in the
presence of a metallocene catalyst.
[0018] "Polymer," as used herein, means a macromolecular compound
prepared by polymerizing monomers of the same or different type.
"Polymer" includes homopolymers, copolymers, terpolymers,
interpolymers, and so on. The term "interpolymer" means a polymer
prepared by the polymerization of at least two types of monomers or
comonomers. It includes, but is not limited to, copolymers (which
usually refers to polymers prepared from two different types of
monomers or comonomers, although it is often used interchangeably
with "interpolymer" to refer to polymers made from three or more
different types of monomers or comonomers), terpolymers (which
usually refers to polymers prepared from three different types of
monomers or comonomers), tetrapolymers (which usually refers to
polymers prepared from four different types of monomers or
comonomers), and the like. The terms "monomer" or "comonomer" are
used interchangeably, and they refer to any compound with a
polymerizable moiety which is added to a reactor in order to
produce a polymer. In those instances in which a polymer is
described as comprising one or more monomers, e.g., a polymer
comprising propylene and ethylene, the polymer, of course,
comprises units derived from the monomers, e.g.,
--CH.sub.2--CH.sub.2--, and not the monomer itself, e.g.,
CH.sub.2.dbd.CH.sub.2.
[0019] "P/E* copolymer" and similar terms, as used herein, means a
propylene/unsaturated comonomer copolymer characterized as having
at least one of the following properties: (i) .sup.13C NMR peaks
corresponding to a regio-error at about 14.6 and about 15.7 ppm,
the peaks of about equal intensity and (ii) a differential scanning
calorimetry (DSC) curve with a T.sub.me that remains essentially
the same and a T.sub.peak that decreases as the amount of
comonomer, i.e., the units derived from ethylene and/or the
unsaturated comonomer(s), in the copolymer is increased. "T.sub.me
" means the temperature at which the melting ends. "T.sub.peak "
means the peak melting temperature. Typically, the copolymers of
this embodiment are characterized by both of these properties. Each
of these properties and their respective measurements are described
in detail in U.S. patent application Ser. No. 10/139,786, filed May
5, 2002 (WO2003040442) which is incorporated herein by
reference.
[0020] These copolymers can be further characterized further as
also having a skewness index, S.sub.ix, greater than about -1.20.
The skewness index is calculated from data obtained from
temperature-rising elution fractionation (TREF). The data is
expressed as a normalized plot of weight fraction as a function of
elution temperature. The molar content of isotactic propylene units
that primarily determines the elution temperature.
[0021] A prominent characteristic of the shape of the curve is the
tailing at lower elution temperature compared to the sharpness or
steepness of the curve at the higher elution temperatures. A
statistic that reflects this type of asymmetry is skewness.
Equation 1 mathematically represents the skewness index, S.sub.ix,
as a measure of this asymmetry. S ix = w i * ( T i - T Max ) 3 3 w
i * ( T i - T Max ) 2 . Equation .times. .times. 1 ##EQU1##
[0022] The value, T.sub.max, is defined as the temperature of the
largest weight fraction eluting between 50 and 90 degrees C. in the
TREF curve. T.sub.i and w.sub.i are the elution temperature and
weight fraction respectively of an arbitrary, i.sup.th fraction in
the TREF distribution. The distributions have been normalized (the
sum of the wi equals 100%) with respect to the total area of the
curve eluting above 30 degrees C. Thus, the index reflects only the
shape of the crystallized polymer. Any uncrystallized polymer
(polymer still in solution at or below 30 degrees C.) is omitted
from the calculation shown in Equation 1.
[0023] The unsaturated comonomers for P/E* copolymers include
C.sub.4-20 .alpha.-olefins, especially C.sub.4-12 .alpha.-olefins
such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene,
1-heptene, 1-octene, 1-decene, 1-dodecene and the like; C.sub.4-20
diolefins, preferably 1,3-butadiene, 1,3-pentadiene, norbomadiene,
5-ethylidene-2-norbomene (ENB) and dicyclopentadiene; C.sub.8-40
vinyl aromatic compounds including sytrene, o-, m-, and
p-methylstyrene, divinylbenzene, vinylbiphenyl, vinylnapthalene;
and halogen-substituted C.sub.8-40 vinyl aromatic compounds such as
chlorostyrene and fluorostyrene. Ethylene and the C.sub.4-12
.alpha.-olefins are the preferred comonomers, and ethylene is an
especially preferred comonomer.
[0024] P/E* copolymers are a unique subset of P/E copolymers. P/E
copolymers include all copolymers of propylene and an unsaturated
comonomer, not just P/E* copolymers. P/E copolymers other than P/E*
copolymers include metallocene-catalyzed copolymers, constrained
geometry catalyst catalyzed copolymers, and Z-N-catalyzed
copolymers. For purposes of this invention, P/E copolymers comprise
50 weight percent or more propylene while EP (ethylene-propylene)
copolymers comprise 51 weight percent or more ethylene. As here
used, "comprise . . . propylene", "comprise . . . ethylene" and
similar terms mean that the polymer comprises units derived from
propylene, ethylene or the like as opposed to the compounds
themselves.
[0025] "Propylene homopolymer" and similar terms mean a polymer
consisting solely or essentially all of units derived from
propylene. "Polypropylene copolymer" and similar terms mean a
polymer comprising units derived from propylene and ethylene and/or
one or more unsaturated comonomers.
[0026] "Ziegler-Natta-catalyzed polymer," "Z-N-catalyzed polymer,"
or similar term means any polymer that is made in the presence of a
Ziegler-Natta catalyst.
[0027] In one embodiment, the present invention is a free-radical
carbon-FRTS-carbon crosslinkable polymeric composition, which
comprises a free-radical degradable polymer, a free-radical
inducing species, and a free radical trapping species having at
least two trapping sites. The polymer is capable of forming free
radicals when induced by the free-radical inducing species.
[0028] In the absence of the free-radical trapping species and when
induced by the free-radical inducing species, the polymer undergoes
a degradation reaction in the presence of the free-radical inducing
species. The degradation reaction can be chain scission or
dehydrohalogenation. The free radical trapping species
substantially suppresses the degradation reaction.
[0029] At the trapping sites, the free-radical trapping species is
graftable onto the polymer after the polymer forms a free radical.
A free-radical carbon-FRTS-carbon crosslinked polymer is yielded.
Preferably, the free-radical carbon-FRTS-carbon crosslinked polymer
will be substantially homogeneously crosslinked.
[0030] A variety of free-radical degradable polymers is useful in
the present invention as the polymer. The free-radical degradable
polymer can be hydrocarbon-based. Suitable free-radical degradable,
hydrocarbon-based polymers include butyl rubber, polyacrylate
rubber, polyisobutene, propylene homopolymers, propylene
copolymers, styrene/butadiene/styrene block copolymers,
styrene/ethylene/butadiene/styrene copolymers, polymers of vinyl
aromatic monomers, vinyl chloride polymers, and blends thereof.
[0031] Preferably, the free-radical degradable, hydrocarbon-based
polymer is selected from the group consisting of isobutene,
propylene, and styrene polymers.
[0032] Preferably, the butyl rubber of the present invention is a
copolymer of isobutylene and isoprene. The isoprene is typically
used in an amount between about 1.0 weight percent and about 3.0
weight percent.
[0033] Examples of propylene polymers useful in the present
invention include propylene homopolymers and P/E copolymers. In
particular, these propylene polymers include polypropylene
elastomers. The propylene polymers can be made by any process and
can be made by Zeigler-Natta, CGC, metallocene, and nonmetallocene,
metal-centered, heteroaryl ligand catalysis.
[0034] Useful propylene copolymers include random, block and graft
copolymers. Exemplary propylene copolymers include Exxon-Mobil
VISTAMAX, Mitsui TAFMER, and VERSIFY.TM. by The Dow Chemical
Company. The density of these copolymers is typically at least
about 0.850, preferably at least about 0.860 and more preferably at
least about 0.865, grams per cubic centimeter (g/cm.sup.3).
[0035] Typically, the maximum density of these propylene copolymers
is about 0.915, preferably the maximum is about 0.900 and more
preferably the maximum is about 0.890 g/cm.sup.3. The weight
average molecular weight (Mw) of these propylene copolymers can
vary widely, but typically it is between about 10,000 and
1,000,000. The polydispersity of these copolymers is typically
between about 2 and about 4.
[0036] These propylene copolymers typically have a melt flow rate
(MFR) of at least about 0.01, preferably at least about 0.05, and
more preferably at least about 0.1. The maximum MFR typically does
not exceed about 2,000, preferably it does not exceed about 1000,
more preferably it does not exceed about 500, further more
preferably it does not exceed about 80 and most preferably it does
not exceed about 50. MFR for copolymers of propylene and ethylene
and/or one or more C.sub.4-C.sub.20 .alpha.-olefins is measured
according to ASTM D-1238, condition L (2.16 kg, 230 degrees
C.).
[0037] Styrene/butadiene/styrene block copolymers useful in the
present invention are a phase-separated system.
Styrene/ethylene/butadiene/styrene copolymers are also useful in
the present invention.
[0038] Polymers of vinyl aromatic monomers are useful in the
present invention. Suitable vinyl aromatic monomers include, but
are not limited to, those vinyl aromatic monomers known for use in
polymerization processes, such as those described in U.S. Pat. Nos.
4,666,987; 4,572,819 and 4,585,825.
[0039] Preferably, the monomer is of the formula: ##STR1## wherein
R' is hydrogen or an alkyl radical containing three carbons or
less, Ar is an aromatic ring structure having from 1 to 3 aromatic
rings with or without alkyl, halo, or haloalkyl substitution,
wherein any alkyl group contains 1 to 6 carbon atoms and haloalkyl
refers to a halo substituted alkyl group. Preferably, Ar is phenyl
or alkylphenyl, wherein alkylphenyl refers to an alkyl substituted
phenyl group, with phenyl being most preferred. Typical vinyl
aromatic monomers which can be used include: styrene,
alpha-methylstyrene, all isomers of vinyl toluene, especially
para-vinyltoluene, all isomers of ethyl styrene, propyl styrene,
vinyl biphenyl, vinyl naphthalene, vinyl anthracene and the like,
and mixtures thereof.
[0040] The vinyl aromatic monomers may also be combined with other
copolymerizable monomers. Examples of such monomers include, but
are not limited to acrylic monomers such as acrylonitrile,
methacrylonitrile, methacrylic acid, methyl methacrylate, acrylic
acid, and methyl acrylate; maleimide, phenylmaleimide, and maleic
anhydride. In addition, the polymerization may be conducted in the
presence of predissolved elastomer to prepare impact modified, or
grafted rubber containing products, examples of which are described
in U.S. Pat. Nos. 3,123,655, 3,346,520, 3,639,522, and
4,409,369.
[0041] The present invention is also applicable to the rigid,
matrix or continuous phase polymer of rubber-modified
monovinylidene aromatic polymer compositions.
[0042] Useful free-radical inducing species include organic
peroxides, Azo free radical initiators, and bicumene. Preferably,
the free-radical inducing species is an organic peroxide. Also,
oxygen-rich environments are preferred for initiating useful
free-radicals. Preferable organic peroxides include dicumyl
peroxide, Vulcup R, and dialkyl peroxides. More preferable, the
organic peroxide is a dialkyl peroxide selected from the group
consisting of 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and
2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne. Most preferably,
the organic peroxide is
2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne.
[0043] The organic peroxide can be added via direct injection.
Preferably, the free-radical inducing species is present in an
amount between about 0.5 weight percent and about 20.0 weight
percent, more preferably, between about 1.0 weight percent and
about 15.0 weight percent, and most preferably, between about 1.5
weight percent and about 10.0 weight percent.
[0044] In addition to or as alternative to the free-radical
inducing species, the polymer can form free radicals when subjected
to shear energy, heat, or radiation. Accordingly, shear energy,
heat, or radiation can act as free-radical inducing species.
Moreover, the free-radical trapping species can act in the presence
of free-radicals generated by shear energy, heat, or radiation as
the free-radical trapping species would act in the presence of free
radicals generated by the previously-described free-radical
inducing species.
[0045] It is believed that when the free-radicals are generated by
an organic peroxide, oxygen, air, shear energy, heat, or radiation,
the combination of the free-radical trapping species and the source
of free-radical is required for carbon-FRTS-carbon crosslinking of
the polymer. Control of this combination determines the molecular
architecture of the crosslinked polymer. Sequential addition of the
free-radical trapping species followed by gradual initiation of
free radicals provides an unprecedented degree of control over the
molecular architecture.
[0046] It is also believed that grafting sites can be initiated on
the polymer and capped with the free-radical trapping species to
form a pendant stable free radical. Later, the pendant stable free
radical can carbon-FRTS-carbon crosslink with a subsequently formed
free radical, imparting desired levels of homogeneity to the
resulting carbon-FRTS-carbon crosslinked polymer.
[0047] Examples of the free radical trapping species useful in the
present invention include hindered amine-derived stable organic
free radicals. Preferably, when the free radical trapping species
is a hindered amine-derived stable organic free radical, it is
selected from the group consisting of multi-functional molecules
having at least two functional groups of 2,2,6,6,-tetramethyl
piperidinyl oxy (TEMPO) and derivatives thereof. More preferably,
the stable organic free radical is a bis-TEMPO. An example of a
bis-TEMPO is
bis(l-oxyl-2,2,6,6-tetramethylpiperidine-4-yl)sebacate. Also, even
more preferably, the stable organic free radical is a
multi-functional molecule having at least two nitroxyl groups
derived from oxo-TEMPO, hydroxy-TEMPO, an ester of hydroxy-TEMPO,
polymer-bound TEMPO, PROXYL, DOXYL, di-tertiary butyl N oxyl,
dimethyl diphenylpyrrolidine-1-oxyl, 4 phosphonoxy TEMPO, or a
metal complex with TEMPO.
[0048] Preferably, the free radical trapping species is present in
an amount between about 0.5 weight percent and about 20.0 weight
percent, more preferably, between about 1.0 weight percent and
about 15.0 weight percent, most preferably, between about 1.5
weight percent and about 10.0 weight percent.
[0049] Preferably, the ratio of the free-radical inducing species
to the free radical trapping species and the concentration of the
free-radical trapping species promote carbon-FRTS-carbon
crosslinking of the polymer. More preferably, the free-radical
inducing species to the free-radical trapping species are present
in a ratio greater than about 1, more preferably, between about
20:1 to about 1:1.
[0050] The free-radical trapping species and the free-radical
inducing species can be combined with the polymer in a variety of
ways, including direct compounding, direct soaking, and direct
injection.
[0051] In an alternate embodiment, the present invention is a
free-radical carbon-FRTS-carbon crosslinkable polymeric
composition, which comprises a free-radical carbon-carbon
crosslinkable polymer, a free-radical inducing species, and a free
radical trapping species having at least two trapping sites. The
polymer is capable of forming free radicals when induced by the
free-radical inducing species.
[0052] In the absence of the free-radical trapping species and when
induced by the free-radical inducing species, the polymer undergoes
a carbon-carbon crosslinking reaction. The free radical trapping
species substantially suppresses the carbon-carbon crosslinking
reaction.
[0053] At the trapping sites, the free-radical trapping species is
graftable onto the polymer after the polymer forms a free radical.
A free-radical carbon-FRTS-carbon crosslinked polymer is yielded.
Preferably, the free-radical carbon-FRTS-carbon crosslinked polymer
will be substantially homogeneously crosslinked.
[0054] A variety of free-radical carbon-carbon crosslinkable
polymers is useful in the present invention as the polymer. The
free-radical carbon-carbon crosslinkable polymer can be
hydrocarbon-based. Suitable free-radical carbon-carbon
crosslinkable, hydrocarbon-based polymers include acrylonitrile
butadiene styrene rubber, chloroprene rubber, chlorosulfonated
polyethylene rubber, ethylene/alpha-olefin copolymers,
ethylene/diene copolymer, ethylene homopolymers,
ethylene/propylene/diene monomers, ethylene/propylene rubbers,
ethylene/styrene interpolymers, ethylene/unsaturated ester
copolymers, fluoropolymers, halogenated polyethylenes, hydrogenated
nitrile butadiene rubber, natural rubber, nitrile rubber,
polybutadiene rubber, silicone rubber, styrene/butadiene rubber,
styrene/butadiene/styrene block copolymers,
styrene/ethylene/butadiene/styrene copolymers, and blends
thereof.
[0055] For the present invention, chloroprene rubbers are generally
polymers of 2-chloro-1,3-butadiene. Preferably, the rubber is
produced by an emulsion polymerization. Additionally, the
polymerization can occur in the presence of sulfur to incorporate
crosslinking in the polymer.
[0056] Preferably, the free-radical carbon-carbon crosslinkable,
hydrocarbon-based polymer is an ethylene polymer.
[0057] With regard to the suitable ethylene polymers, the polymers
generally fall into four main classifications: (1) highly-branched;
(2) heterogeneous linear; (3) homogeneously branched linear; and
(4) homogeneously branched substantially linear. These polymers can
be prepared with Ziegler-Natta catalysts, metallocene or
vanadium-based single-site catalysts, or constrained geometry
single-site catalysts.
[0058] Highly branched ethylene polymers include low density
polyethylene (LDPE). Those polymers can be prepared with a
free-radical initiator at high temperatures and high pressure.
Alternatively, they can be prepared with a coordination catalyst at
high temperatures and relatively low pressures. These polymers have
a density between about 0.910 grams per cubic centimeter and about
0.940 grams per cubic centimeter as measured by ASTM D-792.
[0059] Heterogeneous linear ethylene polymers include linear low
density polyethylene (LLDPE), ultra-low density polyethylene
(ULDPE), very low density polyethylene (VLDPE), and high density
polyethylene (HDPE). Linear low density ethylene polymers have a
density between about 0.850 grams per cubic centimeter and about
0.940 grams per cubic centimeter and a melt index between about
0.01 to about 100 grams per 10 minutes as measured by ASTM 1238,
condition I. Preferably, the melt index is between about 0.1 to
about 50 grams per 10 minutes. Also, preferably, the LLDPE is an
interpolymer of ethylene and one or more other alpha-olefins having
from 3 to 18 carbon atoms, more preferably from 3 to 8 carbon
atoms. Preferred comonomers include 1 -butene, 4-methyl-1-pentene,
1-hexene, and 1-octene.
[0060] Ultra-low density polyethylene and very low density
polyethylene are known interchangeably. These polymers have a
density between about 0.870 grams per cubic centimeter and about
0.910 grams per cubic centimeter. High density ethylene polymers
are generally homopolymers with a density between about 0.941 grams
per cubic centimeter and about 0.965 grams per cubic
centimeter.
[0061] Homogeneously branched linear ethylene polymers include
homogeneous LLDPE. The uniformly branched/homogeneous polymers are
those polymers in which the comonomer is randomly distributed
within a given interpolymer molecule and wherein the interpolymer
molecules have a similar ethylene/comonomer ratio within that
interpolymer.
[0062] Homogeneously-branched substantially linear ethylene
polymers include (a) homopolymers of C.sub.2-C.sub.20 olefins, such
as ethylene, propylene, and 4-methyl-1-pentene, (b) interpolymers
of ethylene with at least one C.sub.3-C.sub.20 alpha-olefin,
C.sub.2-C.sub.20 acetylenically unsaturated monomer,
C.sub.4-C.sub.18 diolefin, or combinations of the monomers, and (c)
interpolymers of ethylene with at least one of the C.sub.3-C.sub.20
alpha-olefins, diolefins, or acetylenically unsaturated monomers in
combination with other unsaturated monomers. These polymers
generally have a density between about 0.850 grams per cubic
centimeter and about 0.970 grams per cubic centimeter. Preferably,
the density is between about 0.85 grams per cubic centimeter and
about 0.955 grams per cubic centimeter, more preferably, between
about 0.850 grams per cubic centimeter and 0.920 grams per cubic
centimeter.
[0063] Ethylene/styrene interpolymers useful in the present
invention include substantially random interpolymers prepared by
polymerizing an olefin monomer (i.e., ethylene, propylene, or
alpha-olefin monomer) with a vinylidene aromatic monomer, hindered
aliphatic vinylidene monomer, or cycloaliphatic vinylidene monomer.
Suitable olefin monomers contain from 2 to 20, preferably from 2 to
12, more preferably from 2 to 8 carbon atoms. Preferred such
monomers include ethylene, propylene, 1-butene, 4-methyl-i-pentene,
1-hexene, and 1-octene. Most preferred are ethylene and a
combination of ethylene with propylene or C.sub.4-.sub.8
alpha-olefins. Optionally, the ethylene/styrene interpolymers
polymerization components can also include ethylenically
unsaturated monomers such as strained ring olefins. Examples of
strained ring olefins include norbornene and C.sub.1-10 alkyl- or
C.sub.6-10 aryl-substituted norbornenes.
[0064] Ethylene/unsaturated ester copolymers useful in the present
invention can be prepared by conventional high-pressure techniques.
The unsaturated esters can be alkyl acrylates, alkyl methacrylates,
or vinyl carboxylates. The alkyl groups can have 1 to 8 carbon
atoms and preferably have 1 to 4 carbon atoms. The carboxylate
groups can have 2 to 8 carbon atoms and preferably have 2 to 5
carbon atoms. The portion of the copolymer attributed to the ester
comonomer can be in the range of about 5 to about 50 percent by
weight based on the weight of the copolymer, and is preferably in
the range of about 15 to about 40 percent by weight. Examples of
the acrylates and methacrylates are ethyl acrylate, methyl
acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate,
n-butyl methacrylate, and 2-ethylhexyl acrylate. Examples of the
vinyl carboxylates are vinyl acetate, vinyl propionate, and vinyl
butanoate. The melt index of the ethylene/unsaturated ester
copolymers can be in the range of about 0.5 to about 50 grams per
10 minutes.
[0065] Halogenated ethylene polymers useful in the present
invention include fluorinated, chlorinated, and brominated olefin
polymers. The base olefin polymer can be a homopolymer or an
interpolymer of olefins having from 2 to 18 carbon atoms.
Preferably, the olefin polymer will be an interpolymer of ethylene
with propylene or an alpha-olefin monomer having 4 to 8 carbon
atoms. Preferred alpha-olefin comonomers include 1-butene,
4-methyl-1-pentene, 1-hexene, and 1-octene. Preferably, the
halogenated olefin polymer is a chlorinated polyethylene.
[0066] Natural rubbers suitable in the present invention include
high molecular weight polymers of isoprene. Preferably, the natural
rubber will have a number average degree of polymerization of about
5000 and a broad molecular weight distribution.
[0067] Preferably, the nitrile rubber of the present invention is a
random copolymer of butadiene and acrylonitrile.
[0068] The polybutadiene rubber useful in the present invention is
preferably a homopolymer of 1,4-butadiene.
[0069] Useful styrene/butadiene rubbers include random copolymers
of styrene and butadiene. Typically, these rubbers are produced by
free radical polymerization. Styrene/butadiene/styrene block
copolymers of the present invention are a phase-separated system.
The styrene/ethylene/butadiene/styrene copolymers are also useful
in the present invention.
[0070] Useful free-radical inducing species include organic
peroxides, Azo free radical initiators, and bicumene. Preferably,
the free-radical inducing species is an organic peroxide. Also,
oxygen-rich environments are preferred for initiating useful
free-radicals. Preferable organic peroxides include dicumyl
peroxide, Vulcup R, and dialkyl peroxides. More preferable, the
organic peroxide is a dialkyl peroxide selected from the group
consisting of 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and
2,5-bis,(tert-butylperoxy)-2,5-dimethyl-3-hexyne. Most preferably,
the organic peroxide is
2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne.
[0071] The organic peroxide can be added via direct injection.
Preferably, the free-radical inducing species is present in an
amount between about 0.5 weight percent and about 20.0 weight
percent, more preferably, between about 1.0 weight percent and
about 15.0 weight percent, and most preferably, between about 1.5
weight percent and about 10.0 weight percent.
[0072] In addition to or as alternative to the free-radical
inducing species, the polymer can form free radicals when subjected
to shear energy, heat, or radiation. Accordingly, shear energy,
heat, or radiation can act as free-radical inducing species.
Moreover, the free-radical trapping species can act in the presence
of free-radicals generated by shear energy, heat, or radiation as
the free-radical trapping species would act in the presence of free
radicals generated by the previously-described free-radical
inducing species.
[0073] It is believed that when the free-radicals are generated by
an organic peroxide, oxygen, air, shear energy, heat, or radiation,
the combination of the free-radical trapping species and the source
of free-radical is required for carbon-FRTS-carbon crosslinking of
the polymer. Control of this combination determines the molecular
architecture of the carbon-FRTS-carbon crosslinked polymer.
Sequential addition of the free-radical trapping species followed
by gradual initiation of free radicals provides an unprecedented
degree of control over the molecular architecture.
[0074] It is also believed that grafting sites can be initiated on
the polymer and capped with the free-radical trapping species to
form a pendant stable free radical. Later, the pendant stable free
radical can carbon-FRTS-carbon crosslink with a subsequently formed
free radical, imparting desired levels of homogeneity to the
resulting carbon-FRTS-carbon crosslinked polymer.
[0075] In yet another embodiment, the present invention is a
free-radical carbon-FRTS-carbon crosslinkable polymeric
composition, which comprises (1) a polymer selected from the group
consisting of free-radical degradable polymers and free-radical
carbon-carbon crosslinkable polymers and (2) a pendant stable free
radical.
[0076] The pendant stable free radical is derived from grafting a
free radical trapping species onto the polymer. Prior to forming
the pendant stable free radical, the free radical trapping species
had at least two trapping sites. After its formation, the pendant
stable free radical has at least one trapping site.
[0077] The polymer is capable of forming free radicals when induced
by a free-radical inducing species. In the absence of the pendant
stable free radical and when induced by a free-radical inducing
species, the polymer is capable of forming free radicals and
preferentially undergoes an undesirable reaction. The undesirable
reaction is a degradation reaction or a carbon-carbon crosslinking
reaction.
[0078] In the free-radical carbon-FRTS-carbon crosslinkable
polymeric composition, the undesirable reaction is substantially
suppressed.
[0079] At the trapping sites, the pendant stable free radical is
graftable onto the polymer after the polymer forms a free radical.
A free-radical carbon-FRTS-carbon crosslinked polymer is yielded.
The carbon-FRTS-carbon crosslinked polymer comprises the polymer
crosslinked to the pendant stable free radical. Preferably, the
free-radical carbon-FRTS-carbon crosslinked polymer will be
substantially homogeneously coupled.
[0080] The free-radical trapping species and the free-radical
inducing species can be combined with the polymer in a variety of
ways, including direct compounding, direct soaking, and direct
injection.
[0081] In an alternate embodiment, the present invention is a
process for preparing a free-radical carbon-FRTS-carbon
crosslinkable polymer. The first step of the process is preparing a
polymer-matrix mixture by mixing its components. The components
include a free-radical degradable polymer, a free-radical inducing
species, and a free radical trapping species having at least two
trapping sites. The free radical trapping species substantially
suppresses the degradation reaction. In the second step, the
polymer is grafted through the free-radical trapping species.
[0082] In this embodiment, it is possible to control the molecular
architecture of the resulting free-radical carbon-FRTS-carbon
crosslinked polymer. To do so, the rate of adding the free-radical
inducing species in the first step should (1) be controlled and (2)
follows the addition or occur simultaneously with the addition of
the free-radical trapping species. Preferably, the free-radical
inducing species will be added following addition of the
free-radical trapping species (that is, in a second step and the
grafting will occur in a third step).
[0083] It is possible to substitute a pendant stable free radical
for the free-radical trapping species. To that end, the
free-radical trapping species can be separately grafted onto the
polymer to form a pendant stable free radical in an inert
atmosphere. The polymer matrix will then include the polymer, the
pendant stable free radical, and a free-radical inducing
species.
[0084] In an alternate embodiment, the present invention is a
process for preparing a free-radical carbon-FRTS-carbon
crosslinkable polymer. The first step of the process is preparing a
polymer-matrix mixture by mixing its components. The components
include a free-radical carbon-carbon crosslinkable polymer, a
free-radical inducing species, and a free radical trapping species
having at least two trapping sites. The free radical trapping
species substantially suppresses the carbon-carbon crosslinking
reaction. In the second step, the polymer is grafted through the
free-radical trapping species.
[0085] In this embodiment, it is possible to control the molecular
architecture of the resulting free-radical carbon-FRTS-carbon
crosslinked polymer. To do so, the rate of adding the free-radical
inducing species in the first step should (1) be controlled and (2)
follows the addition or occur simultaneously with the addition of
the free-radical trapping species. Preferably, the free-radical
inducing species will be added following addition of the
free-radical trapping species (that is, in a second step and the
grafting will occur in a third step).
[0086] It is possible to substitute a pendant stable free radical
for the free-radical trapping species. To that end, the
free-radical trapping species can be separately grafted onto the
polymer to form a pendant stable free radical in an inert
atmosphere. The polymer matrix will then include the polymer, the
pendant stable free radical, and a free-radical inducing
species.
[0087] In a preferred embodiment, the present invention is an
article of manufacture prepared from the free-radical
carbon-FRTS-carbon crosslinkable polymer composition. Any number of
processes can be used to prepare the articles of manufacture.
Specifically useful processes include injection molding, extrusion,
compression molding, rotational molding, thermoforming,
blowmolding, powder coating, Banbury batch mixers, fiber spinning,
and calendaring.
[0088] Suitable articles of manufacture include wire-and-cable
insulations, wire-and-cable semiconductive articles, wire-and-cable
coatings and jackets, cable accessories, shoe soles, multicomponent
shoe soles (including polymers of different densities and type),
weather stripping, gaskets, profiles, durable goods, rigid
ultradrawn tape, run flat tire inserts, construction panels,
composites (e.g., wood composites), pipes, foams, blown films, and
fibers (including binder fibers and elastic fibers).
EXAMPLES
[0089] The following non-limiting examples illustrate the
invention.
Comparative Examples 1-3 and Examples 4-5
[0090] Three comparative examples and two examples of the present
invention were prepared with a polypropylene elastomer, having an
ethylene content of 15 weight percent, a melt flow rate of 2 grams
per 10 minutes, and a density of 0.858 grams per cubic centimeter.
The melt flow rate was measured at 230 degrees Celsius according to
ASTM D-1238.
[0091] Each of the formulations shown in Table I, excluding the
peroxide, was prepared in a Brabender mixer to make 40 grams
samples at 110 degrees Celsius for 3 minutes. The peroxide was
subsequently added. The composition was compounded for 4 additional
minutes.
[0092] The PROSTAB.TM. 5415
bis(1-oxyl-2,2,6,6-tetramethylpiperidine-4-yl)sebacate (the
"bis-TEMPO") was commercially available from the Ciba Specialty
Chemicals, Inc. The Luperox.TM. 130
2,5-Bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne organic peroxide
was commercially available from Atofina.
[0093] The reaction kinetics were investigated using a moving die
rheometer (MDR) at 182 degrees Celsius. Tensile strength and hot
creep were measured on plaques of 0.03 inch (30 mil) thickness that
were prepared by compression molding for 10 minutes at 110 degrees
Celsius, followed by 70 minutes at 180 degrees Celsius. Tensile
strength (stress at maximum load) was determined at room
temperature in accordance with ASTM D638-00 (at displacement rate
of 2 inch/minute). Hot Creep properties were determined at three
different temperatures (50, 100 and 150 degrees Celsius) in
accordance with ICEA Publication T-28-562-1995 ("Test Method for
Measurement of Hot Creep of Polymeric Insulations" dated March 1995
from Insulated Cable Engineers Association, Inc). When the test
specimen without breaking achieved the maximum limits of the
testing equipment for Hot Creep, the results were reported as
maximum. The results are reported in Table I.
[0094] For each evaluated composition, the MDR generated torque
versus time data. In addition to the set temperature of 182 degrees
Celsius, the MDR was set for a frequency of 100 cycles per minute
and an arc of 0.5 degrees. The test specimens weighed about 5 grams
and were placed between Mylar.TM. sheets and then into the MDR for
evaluation. The set temperature and evaluation time were set
depending on the end-use application and the composition.
[0095] FIG. 1 showed torque-time curves at 182 degrees Celsius for
Comparative Example 3 and Example 5. FIG. 2 show torque-time curves
at 182 degrees Celsius for Examples 4 and 5. TABLE-US-00001 TABLE I
Component C. Ex. 1 C. Ex. 2 C. Ex. 3 Ex. 4 Ex. 5 polypropylene
100.0 98.75 98.0 95.75 95.0 bis-TEMPO 3.0 3.0 Luperox 130 1.25 2.0
1.25 2.0 Tensile Strength (pounds per square inch (psi)) room
temperature 1316 997 1267 1086 Enhanced Hot Creep (20 N/cm.sup.2,
15 minutes) 50 degrees Celsius 119.16 Maximum 50.92 37.80 100
degrees Celsius Broke Broke Maximum 279.27 150 degrees Celsius
Broke Broke Maximum 264.17
Comparative Examples 6-8 and Examples 9-12
[0096] Three comparative examples and four examples were prepared
with a polypropylene elastomer, having an ethylene content of 15
weight percent, a melt flow rate of 2 grams per 10 minutes, and a
density of 0.858 grains per cubic centimeter. The melt flow rate
was measured at 230 degrees Celsius according to ASTM D-1238.
[0097] Each of the formulations shown in Table II, excluding the
peroxide, was prepared in a Brabender mixer to make 40 grams
samples at 110 degrees Celsius for 3 minutes. The peroxide was
subsequently added. The composition was compounded for 4 additional
minutes.
[0098] The PROSTAB.TM. 5415 bis-TEMPO was commercially available
from the Ciba Specialty Corporation. The Dicup R.TM. organic
peroxide was commercially available from Geo Specialty Chemicals
while the Luperox.TM. 130 organic peroxide was commercially
available from Atofina.
[0099] The reaction kinetics were investigated using a moving die
rheometer (MDR) at 182 degrees Celsius. The results are reported in
Table II.
[0100] For each evaluated composition, the MDR generated torque
versus time data. In addition to the set temperature of 182 degrees
Celsius, the MDR was set for a frequency of 100 cycles per minute
and an arc of 0.5 degrees. The test specimens weighed about 5 grams
and were placed between Mylar.TM. sheets and then into the
[0101] MDR for evaluation. The set temperature and evaluation time
were set depending on the end-use application and the composition.
TABLE-US-00002 TABLE II C. C. C. Component Ex. 6 Ex. 7 Ex. 8 Ex. 9
Ex. 10 Ex. 11 Ex. 12 polypropylene 98.0 98.0 96.75 95.0 95.0 95.75
96.25 bis-TEMPO 3.0 3.0 3.0 3.0 3.0 Dicup R 2.0 2.0 Luperox 130 2.0
0.25 2.0 1.25 0.75 MDR: 182 degrees Celsius Time (minutes) 12 12
120 12 60 60 60 Minimum 0.01 0.02 0.29 0.36 0.34 0.33 0.30 Torque,
M.sub.L (lb- in) Maximum 0.03 0.03 0.35 0.87 3.31 2.60 0.63 Torque,
M.sub.H (lb-in) Final Torque, 0.02 0.03 0.33 0.83 2.72 2.45 0.56
M.sub.F (lb-in) Onset of torque N/A N/A 4.00 0.85 1.00 1.25 4.00
increase (min)
Comiparative Example 13 and Examples 14-17
[0102] A comparative example and four examples were prepared with a
polypropylene elastomer, having an ethylene content of 12 weight
percent, a melt flow rate of 8 grams per 10 minutes, and a density
of 0.866 grams per cubic centimeter. The melt flow rate was
measured at 230 degrees Celsius according to ASTM D-1238.
[0103] Each of the formulations shown in Table III, excluding the
peroxide, was prepared in a preheated 300-cc Haake bowl at 100
degrees Celsius and allowed to melt. The bowl was sealed by the
bowl ram, and the components were stirred at 40 rpm.
[0104] When the polymer melted as demonstrated by a recovering
temperature and stabilized torque, the ram was raised. A nitrogen
purge was introduced through a feed port into the bowl. The
peroxide was added. Next, the ram was lowered into the feed port to
seal the reaction vessel. The flow of nitrogen was
discontinued.
[0105] When the temperature of the molten polymer composition
reached the desired reaction temperature, the bowl was operated for
three minutes. Next, the rotors were stopped, and the polymer
mixture was removed, pressed into a flat patty, and allowed to cool
to room temperature.
[0106] The test specimens were prepared by compression molding. The
compositions were melted at 100 degrees Celsius for 3 minutes.
Then, they were compression molded at 5.5 MPa for 2 minutes.
Finally, the molded materials were quenched in a press equilibrated
at room temperature.
[0107] Then, the test specimens were cured at 180 degrees Celsius
in a compression molded press for 20 minutes.
[0108] Tensile strength (stress at maximum load) and tensile
elongation (strain at break) were determined at room temperature in
accordance with ASTM 1708 at a displacement rate of 5 inch/minute.
The gel level was determined by xylene extraction (ASTM 2765). The
results are reported in Table III.
[0109] The PROSTAB.TM. 5415 bis-TEMPO was commercially available
from the Ciba Specialty Corporation. The Luperox.TM. 130 organic
peroxide was commercially available from Atofina. TABLE-US-00003
TABLE III Component C. Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17
polypropylene 100.0 97.2 95.4 94.4 90.8 bis-TEMPO 1.8 3.6 3.6 7.2
Luperox 130 1.0 1.0 2.0 2.0 Gel Content (%) 79 85 70 77 Tensile
Strength 19 16 16 15 15 (MPa) Tensile Elongation (%) 1015 1001 903
910 881
Comparative Example 18 and Examples 19-20
[0110] A comparative example and two examples were prepared with a
propylene homopolymer, having a melt flow rate of 9 grams per 10
minutes and a density of 0.900 grams per cubic centimeter. The melt
flow rate was measured at 230 degrees Celsius according to ASTM
D-1238.
[0111] Each of the formulations shown in Table IV, excluding the
peroxide, was prepared in a preheated 300-cc Haake bowl at 170
degrees Celsius and allowed to melt. The bowl was sealed by the
bowl ram, and the components were stirred at 40 rpm.
[0112] When the polymer melted as demonstrated by a recovering
temperature and stabilized torque, the ram was raised. A nitrogen
purge was introduced through a feed port into the bowl. The
peroxide was added. Next, the ram was lowered into the feed port to
seal the reaction vessel. The flow of nitrogen was
discontinued.
[0113] When the temperature of the molten polymer composition
reached the desired reaction temperature, the bowl was operated for
three minutes. Next, the rotors were stopped, and the polymer
mixture was removed, pressed into a flat patty, and allowed to cool
to room temperature.
[0114] The test specimens were prepared by compression molding. The
compositions were melted at 170 degrees Celsius for 3 minutes.
Then, they were compression molded at 5.5 MPa for 2 minutes.
Finally, the molded materials were quenched in a press equilibrated
at room temperature.
[0115] Then, the test specimens were cured at 180 degrees Celsius
in a compression molded press for 20 minutes.
[0116] Tensile strength (stress at maximum load) and tensile
elongation (strain at break) were determined at room temperature in
accordance with ASTM 1708 at a displacement rate of 5 inch/minute.
The gel level was determined by xylene extraction (ASTM 2765). The
results are reported in Table IV.
[0117] The PROSTAB.TM. 5415 bis-TEMPO was commercially available
from the Ciba Specialty Corporation. The Luperox.TM. 130 organic
peroxide was commercially available from Atofina. TABLE-US-00004
TABLE IV Component C. Ex. 18 Ex. 19 Ex. 20 polypropylene 100.0 97.2
94.4 bis-TEMPO 1.8 3.6 Luperox 130 1.0 2.0 Gel Content (%) 57 89
Tensile Strength (MPa) 39 35 32 Tensile Elongation (%) 39 127
246
Comparative Example 21 and Example 22
[0118] A comparative example and an example of the present
invention were prepared with a polypropylene elastomer, having an
ethylene content of 12 weight percent, a melt flow rate of 8 grams
per 10 minutes, and a density of 0.866 grams per cubic centimeter.
The melt flow rate was measured at 230 degrees Celsius according to
ASTM D-1238.
[0119] Each of the formulations shown in Table V, excluding the
peroxide, was prepared in a preheated 300-cc Haake bowl at 100
degrees Celsius and allowed to melt. The bowl was sealed by the
bowl ram, and the components were stirred at 40 rpm.
[0120] When the polymer melted as demonstrated by a recovering
temperature and stabilized torque, the ram was raised. A nitrogen
purge was introduced through a feed port into the bowl. The
peroxide was added. Next, the ram was lowered into the feed port to
seal the reaction vessel. The flow of nitrogen was
discontinued.
[0121] When the temperature of the molten polymer composition
reached the desired reaction temperature, the bowl was operated for
three minutes. Next, the rotors were stopped, and the polymer
mixture was removed, pressed into a flat patty, and allowed to cool
to room temperature.
[0122] The test specimens were then crosslinked using an e-beam
crosslinking technique under nitrogen atmosphere and at 3.2 mRad
per pass. The test specimens were allowed to cool to room
temperature between successive e-beam passes. The number of passes
is reported in Table V.
[0123] The gel level was determined by xylene extraction (ASTM
2765). The results are reported in Table III.
[0124] The PROSTAB.TM. 5415 bis-TEMPO was commercially available
from the Ciba Specialty Corporation TABLE-US-00005 TABLE V
Component C. Ex. 21 Ex. 22 polypropylene 100.0 99.4 bis-TEMPO 0.6
Number of Passes 9 6 Gel Content (%) 34 65
Comparative Examples 23-28 and Examples 29-31
[0125] Six comparative examples and three examples of the present
invention were prepared with a blended butyl rubber.
[0126] Each of the formulations shown in Table VI, excluding the
peroxide, was prepared in a Brabender mixer to make 40 grams
samples at a specified temperature for 3 minutes. (The temperature
was either 95 degrees Celsius or 124 degrees Celsius. The
temperature selected was to avoid slippage of the free-radical
trapping species. The higher concentration of the free-radical
trapping species required mixing at the lower temperature.) The
peroxide was subsequently added. The composition was compounded for
4 additional minutes.
[0127] The G&E blended butyl rubber (CAS Number 9010-85-9) was
commercially available from Goldsmith & Eggleton, Inc. The
PROSTAB.TM. 5415 bis-TEMPO was commercially available from the Ciba
Specialty Chemicals, Inc. The Luperox.TM. 130
2,5-Bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne organic peroxide
was commercially available from Atofina.
[0128] The reaction kinetics were investigated using a moving die
rheometer (MDR) at 160 degrees Celsius, 182 degrees Celsius, and
200 degrees Celsius. The results are reported in Table VI.
[0129] For each evaluated composition, the MDR generated torque
versus time data. In addition to the set temperature, the MDR was
set for a frequency of 100 cycles per minute and an arc of 0.5
degrees. The test specimens weighed about 5 grams and were placed
between Mylar.TM. sheets and then into the MDR for evaluation. The
set temperature and evaluation time were set depending on the
end-use application and the composition.
[0130] All materials retained good flexibility. That is, they were
not brittle when handled. TABLE-US-00006 TABLE VI Component C. Ex.
23 C. Ex. 24 C. Ex. 25 C. Ex. 26 C. Ex. 27 C. Ex. 28 Ex. 29 Ex. 30
Ex. 31 Butyl rubber 99.25 98.75 98.0 96.25 95.75 95.0 90.0 87.0
85.0 Bis-TEMPO 3.0 3.0 3.0 6.0 9.0 9.0 Luperox 130 0.75 1.25 2.0
0.75 1.25 2.0 4.0 4.0 6.0 Mixing Temperature (degrees Celsius) 124
124 124 124 124 124 95 95 95 MDR: 160 degrees Celsius, 240 minutes
Minimum Torque, M.sub.L (lb-in) 0.00 0.63 0.73 0.68 0.55 0.34 0.49
Maximum Torque, M.sub.H (lb-in) 0.00 0.63 0.82 0.90 0.88 0.69 0.71
Final Torque, M.sub.F (lb-in) 0.00 0.63 0.76 0.75 0.55 0.67 0.62
M.sub.H-M.sub.L (lb-in) 0.00 0.00 0.09 0.22 0.33 0.35 0.22
M.sub.F-M.sub.L (lb-in) 0.00 0.00 0.03 0.07 0.00 0.33 0.13 Onset of
torque increase (min) 27.0 53.0 38.0 MDR: 182 degrees Celsius, 60
minutes Minimum Torque, M.sub.L (lb-in) 0.00 0.50 0.50 0.49 0.34
0.4 0.34 Maximum Torque, M.sub.H (lb-in) 0.00 0.55 0.68 0.82 0.95
1.04 0.73 Final Torque, M.sub.F (lb-in) 0.00 0.49 0.60 0.07 0.03
0.95 0.71 M.sub.H-M.sub.L (lb-in) 0.00 0.05 0.18 0.33 0.61 0.70
0.39 M.sub.F-M.sub.L (lb-in) 0.00 -0.01 0.10 -0.42 -0.31 0.61 0.37
Onset of torque increase (min) 1.5 2.0 2.5 MDR: 200 degrees
Celsius; 12 minutes Minimum Torque, M.sub.L (lb-in) 0.00 0.00 0.00
0.43 0.42 0.41 0.30 0.26 0.26 Maximum Torque, M.sub.H (lb-in) 0.00
0.01 0.00 0.49 0.60 0.61 0.67 0.80 0.69 Final Torque, M.sub.F
(lb-in) 0.00 0.01 0.00 0.48 0.47 0.02 0.01 0.43 0.34
M.sub.H-M.sub.L (lb-in) 0.00 0.01 0.00 0.06 0.18 0.20 0.37 0.54
0.43 M.sub.F-M.sub.L (lb-in) 0.00 0.01 0.00 0.05 0.05 -0.39 -0.29
0.17 0.08 Onset of torque increase (min) 0.7 0.8 1.0
Comparative Example 32 and Example 33
[0131] One comparative example and one examples of the present
invention were prepared with a vinyl chloride/vinyl
acetate/hydroxyl alkyl acrylate terpolymer, having a vinyl chloride
content of 81 percent and a vinyl acetate content of 4 percent.
[0132] Each of the formulations, excluding the peroxide, was
prepared in a Brabender mixer to make 40 grams samples at 125
degrees Celsius for 3 minutes. The peroxide was subsequently added.
The composition was compounded for 4 additional minutes.
[0133] The Comparative Example 32 formulation contained 98 weight
percent of the terpolymer and 2 weight percent of Luperox.TM. 130
organic peroxide. The Example 33 formulation contained 95 weight
percent of the terpolymer, 2 weight percent of Luperox.TM. 130
organic peroxide, and 3 weight percent of PROSTAB.TM. 5415
bis-TEMPO.
[0134] The terpolymer was commercially available from The Dow
Chemical Company as UCAR.TM. VAGC vinyl chloride/vinyl
acetate/hydroxyl alkyl acrylate terpolymer. The PROSTAB.TM. 5415
bis-TEMPO was commercially available from the Ciba Specialty
Chemicals, Inc. The Luperox.TM. 130 organic peroxide was
commercially available from Atofina.
[0135] The reaction kinetics were investigated using a moving die
rheometer (MDR). FIG. 3 showed torque-time curves at 182 degrees
Celsius for Comparative Example 32 and Example 33.
Comparative Examples 34-36 and Example 37-38
[0136] Three comparative examples and two examples of the present
invention were prepared with a low density polyethylene, having a
melt index of 2.4 g/10 minutes, I21/I2 of 52, a density of 0.9200
grams per cubic centimeter, a polydispersity (Mw/Mn) of 3.54, and a
melting point of 110.2 degrees Celsius. Each of the formulations
shown in Table IV, excluding the peroxide, was prepared in a
Brabender mixer at 125 degrees Celsius for 3 minutes. The peroxide
was subsequently added. The composition was compounded for 4
additional minutes.
[0137] The low density polyethylene was commercially available from
The Dow Chemical Company. The PROSTAB.TM. 5415 bis-TEMPO was
commercially available from the Ciba Specialty Corporation. The
Luperox.TM. 130 organic peroxide was commercially available from
Atofina.
[0138] The reaction kinetics were investigated using MDR at 200
degrees Celsius. Tensile strength and tensile elongation were
measured on plaques of 0.05 inch (50 mil) thickness that were
prepared by compression molding for 10 minutes at 125 degrees
Celsius, followed by 70 minutes at 180 degrees Celsius. Tensile
strength (stress at maximum load) and tensile elongation (strain at
break) were determined at room temperature in accordance with ASTM
D638-00 (at displacement rate of 2 inch/minute). The results are
reported in Table VII. TABLE-US-00007 TABLE VII Component C. Ex. 34
C. Ex. 35 C. Ex. 36 Ex. 37 Ex. 38 LDPE 100 99.5 99.0 96.0 95.5
bis-TEMPO 3.0 3.0 Luperox 130 0.5 1.0 1.0 1.5 MDR: 200 degrees
Celsius Time (minutes) 10 20 20 20 Minimum 0.13 0.15 0.09 0.09
Torque, M.sub.L (lb-in) Maximum 1.4 2.75 0.99 3.33 Torque, M.sub.H
(lb-in) Final Torque, 1.4 2.74 0.82 2.82 M.sub.F (lb-in)
M.sub.H-M.sub.L (lb-in) 1.27 2.60 0.90 3.24 M.sub.F-M.sub.L (lb-in)
1.27 2.59 0.73 2.73 Onset of torque 0.50 0.60 1.00 0.80 increase
(min) Tensile Strength (pounds per square inch (psi)) room
temperature 1856 3322 3117 2919 Tensile Elongation (%) room
temperature 531 435 534 457
* * * * *